Pre-concentration of Uranium (VI) using bulk liquid and supported liquid membrane systems optimized containing bis(2-ethylhexyl) phosphoric acid as carrier in low concentrations

The present study describes the pre-concentration of Uranium (VI) from nitric acid solutions (0.100 mg/L) by using bulk liquid membrane (BLM) and supported liquid membrane (SLM) systems. The transport of Uranium (VI) through both membrane systems was studied using low concentration of bis(2-ethyl hexyl) phosphoric acid (D2EHPA) as carrier in kerosene solvent which favors the removal of Uranium (VI) traces (0.001 or 0.004 mol/L). The stripping used was a mixture of phosphoric acid and citric acid, with concentrations ranging from 0.150 mol/L up to around 0.600 mol/L, which improves the removal of the Uranium (VI). In the case of SLM, the polymeric supports used were homemade Polysulfone membranes (PSf) and commercial Polyvinylidene Fluoride membranes from Millipore (PVDF). The kinetics of the uranyl ion transport system was studied for up to 24 h under fixed physical and chemical conditions. Maximum extraction values obtained were above 95%, and recovery yields were in the range 57-79% for the BLM and 90% for the SLM. Pre-concentration systems in both kinds of membrane systems are properly demonstrated and presented in this paper.